Grey spot on BP belly?

[aplasticchair]

I have a florida kingsnake, as well as a sand boa. Never seen this problem before, was wondering if it's a problem I should be concerned with. My baby ball python has a grey (bruise looking) spot on his lower belly near his tail end. Anyone have an idea what it could be? image shown was slightly edited so the mark could be seen easier. Thanks in advance for any advice/help!

[jjhill001]

Try wiping it off?

[Aaron_S]

I don't see any grey spots other than the regular belly colour.